If you are handholding you will never get right on the nodal point - dab of nailvarnish or otherwise - but one technique I've occasionally used to get pretty close (within a couple of milimetres) is to hang a plumbline round the lens near the nodal point on a little noose and line the plumb-bob up with some fixed point on the ground. That way you know that the camera is rotating very near the nodal point in the horizontal plane at least. Vertical is another matter. Provided you don't have acres of foreground this works quite well.
Although that said see my handheld of the Monastry of Grand Chartreuse on this page:http://web.mac.com/gfstokes/iWeb/796EF5B2-091E-448B-B29E-F84C6D89BCD0/Autopano%20Pro%20Tests.html
as stiched with the Autopano Pro demo. A really nasty handheld where I was miles off the nodal point and included acres of foreground but Autopano has sorted it out very well indeed.
One futher point - the panosaurus claims it will hold up to 3 pounds of camera and lens steady. I think that in real life you could get away with 4 or 5 pounds on a still day. I've used it with my aging Canon 300D with a variety of lenses and its been pretty solid with all of them. You might have a problem in strong wind, but it will probably be your tripod that flexes before the panosaurus does.